Distance measurements of this type are of major importance in ophthalmology. In particular, the axial length of the eye, that is the distance between cornea and retina, is of major importance in many medical procedures. However, the measurement of the distance from measurement points on tissue surface in the interior of the eye presents considerable difficulties since the eye itself must not be injured by the measuring tools used.
The known measurement methods for measuring the eye are therefore extraordinarily expensive and inaccurate.